This disclosure relates generally to object detection. More particularly, this disclosure relates to the collection of hyperspectral and polarimetric data for material detection and identification.
The measurement and interpretation of polarized electromagnetic radiation is useful in a multitude of contexts, including for material detection and identification. The polarization state of reflected or emitted electromagnetic radiation may indicate a change in observed material. For example, different natural resources may reflect electromagnetic radiation in different polarization states. Additionally, some man-made objects may have unique polarimetric characteristics that would distinguish them from surrounding environments.
Likewise, hyperspectral imaging is also useful in material identification, allowing the chemical composition of targets to be characterized based on the spectroscopic data obtained from the dispersion of the observed electromagnetic radiation into their constituent spectral bands.
To obtain both hyperspectral and polarimetric data for a given target, two independent sensors (i.e. a hyperspectral sensor and a polarimetric sensor) are commonly used. Where these sensors are on separate hosts, simultaneous imaging can occur, but only with difficulty as the electromagnetic radiation is subject to different conditions, such as viewing angle and illumination, for the hyperspectral and the polarimetric analysis. Where the sensors are on a common host, an amplitude beam splitter or other similar optical component is needed to co-align the separate fields of view, adding to complexity and expense.
The present application provides, among other things, improvements over known techniques to collect hyperspectral and polarimetric data, and in particular to collect hyperspectral and polarimetric data that is both spatially and temporally coincident.